The foodborne pathogen Listeria monocytogenes resists environmental stresses by forming biofilms. Because this pathogen transmits between the environment and the host, it must adapt to temperature as an environmental stress. In this study, we aimed to identify which proteins were present depending on the temperature in the biofilms of L. monocytogenes EGD-e. Proteins in the supernatants of biofilms formed at 25°C and 37°C were compared using two-dimensional gel electrophoresis and liquid chromatography with tandem mass spectrometry. The larger number of extracytoplasmic proteins associated with cell wall/membrane/envelop biogenesis was identified from the supernatant of biofilms formed at 25°C (7) than those at 37°C (0). Among the 16 extracytoplasmic proteins detected only at 25°C, three were peptidases, namely Spl, Cwh, and Lmo0186. Moreover, mRNA expression of the three peptidases was higher at 25°C than at 37°C. Interestingly, this adaptation of gene expression to temperature was present in sessile cells but not in dispersed cells. After inhibiting the activity of extracytoplasmic peptidases with a protease inhibitor, we noted that the levels of biofilm biomass increased with higher concentrations of the protease inhibitor only when L. monocytogenes grew biofilms at 25°C and not at 37°C. Overall, our data suggest an effect of temperature on the presence of peptidases in L. monocytogenes biofilms. Additionally, increasing the levels of extracytoplasmic peptidases in biofilms is likely a unique feature for sessile L. monocytogenes that causes a naturally occurring breakdown of biofilms and facilitates the pathogen exiting biofilms and disseminating into the environment.

中文翻译：

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蛋白质组学分析揭示了单核细胞增生李斯特菌EGD-e生物膜外蛋白质组中胞外肽酶的温度依赖性存在。

食源性单核细胞增生李斯特氏菌通过形成生物膜来抵抗环境压力。由于这种病原体在环境和宿主之间传播，因此它必须适应作为环境压力的温度。在这项研究中，我们旨在根据单核细胞增生李斯特菌生物膜中的温度来鉴定存在哪些蛋白质。EGD-e。使用二维凝胶电泳和液相色谱-串联质谱法比较在25°C和37°C形成的生物膜上清液中的蛋白质。从在25°C（7）下形成的生物膜的上清液中鉴定出与在37°C（0）下形成的生物膜的上清液相关的与细胞壁/膜/包膜生物发生相关的胞外蛋白数量更多。仅在25°C下检测到的16种胞质外蛋白中，有3种是肽酶，即Spl，Cwh和Lmo0186。此外，三个肽酶的mRNA表达在25℃比在37℃更高。有趣的是，基因表达对温度的这种适应性存在于无柄细胞中而不存在于分散的细胞中。用蛋白酶抑制剂抑制胞外肽酶的活性后，单核细胞增生李斯特菌在25°C而不是37°C时生长生物膜。总的来说，我们的数据表明温度对单核细胞增生李斯特菌生物膜中肽酶的存在有影响。另外，增加无生物的单核细胞增生李斯特氏菌的生物膜中胞外肽酶的水平可能是独特的特征，其导致生物膜的自然发生分解并促进病原体离开生物膜并散布到环境中。